This invention concerns the application and removal of pressure adhesive sheet layers, such as masking tape used in the manufacture of printed circuit boards. The manufacture of PC boards currently involves the plating of contacts along one or both sides of the PC board. The contacts are most commonly plated with gold by an electrodeposition process, involving immersion of the side of the PC board in a gold salt bath. The extremely high cost of gold metal as well as a need for a clear border between gold fingers and the rest of the board has led to the use of lengths of masking tape applied to the side surfaces of the board to accurately limit the region immersed in the plating solution. The pressure adhesive masking tape is applied manually or by machine, and is manually removed after the plating process is complete. The tape must be tightly adherent in order to effectively mask the area of the PC board sought to be isolated from the plating solution, and thus the tape removal process has created a labor intensive step in the process of manufacture of circuit boards as it is now practiced.
Prior attempts have been made to mechanize or automate this process by mechanical stripping of the tape, essentially by vise gripping of the "tail" section and movement of the board by conveyor rollers. Such approach has not been able to be implemented with an acceptable level of reliability.
In copending application Ser. No. 351,989, filed Feb. 24, 1982, there is disclosed a process and apparatus for automatically accomplishing the stripping of such masking tape, which involves the use of rollers which adhere to the outside of the tape and enable winding up of the stripped tape. In order to facilitate the stripping, an area of localized low adhesion is established at the lead end of the PC board. This is disclosed as being achieved by a release agent, or a special configuration of masking tape.
It is an object of the present invention to provide a process and preform which enables practice of that process with a highly reliable and effective establishment of non-adhesive areas beneath the masking tape.
It is another object of the present invention to provide a disposable roller cover for use in the removal process.